Carbon monoxide (CO) poisoning is a well-known phenomenon, and for the most part, its pathophysiology is well-understood. Each year in the United States there are close to 500 deaths, over 15,000 emergency room visits, and approximately 4,000 hospitalizations due to CO poisoning. A review of pertinent background information on the subject can be found at the following Internet links. http://www.cdc.gov/co/faqs.htm, and http://en.wikipedia.org/wiki/Carbon_monoxide_poisoning
Current Treatment: At present, the treatment of CO poisoning can be thought of as having three main components: first aid, standard oxygen therapy, and hyperbaric oxygen. First aid consists of immediately removing the victim from the source of CO exposure. Standard oxygen therapy consists of administering 100% oxygen through a tight-fitting non-rebreather mask. This technique results in the administration of high concentrations of oxygen at a level of between 60-90% O2. However, for patients with severe chronic obstructive pulmonary disease (COPD) such high levels of oxygen can actually inhibit their respiratory drive and thus lead to decreased ventilation. Hyperbaric oxygen (HBO) requires the use of a hyperbaric chamber which is found in very select locations and is not always readily available. However, a review published in 2005 on the use of HBO concluded: “There is conflicting evidence regarding the efficacy of HBO treatment for patients with CO poisoning. Methodological shortcomings are evident in all published trials, with empiric evidence of bias in some, particularly those that suggest a benefit of HBO. Bayesian analysis further illustrates the uncertainty about a meaningful clinical benefit. Consequently, firm guidelines regarding the use of HBO for patients with CO poisoning cannot be established. Further research is needed to better define the role of HBO, if any, in the treatment of CO poisoning.”
Scientific Background: Following exposure, CO binds to hemoglobin to form carboxyhemoglobin. The affinity between CO and hemoglobin is approximately 230 times stronger than the affinity between oxygen and hemoglobin. Therefore, CO binds to hemoglobin in a much greater likelihood than oxygen. Carbon monoxide also binds to the hemeprotein known as myoglobin. Carbon monoxide also has a high affinity for myoglobin at about 60 times greater than that of oxygen. It should also be noted that a delayed return of symptoms of CO poisoning have been reported and is associated with a recurrence of increased carboxyhemoglobin levels following an initial reduction in the level of carboxyhemoglobin. This effect may be due to a late release of CO from myoglobin, which then subsequently binds to hemoglobin.
Although previously not associated with carbon monoxide poisoning, the basic principle of extracorporial therapy involves the circulation of blood outside of the body. Extracorporial treatment is well-established in the practice of medicine, and the most well-known example is hemodialysis. Another common example is cardiac bypass surgery during which an external pump is used instead of the heart which allows surgeons to operate on a non-beating heart. Two less well-known examples are plasmapharesis and peripheral blood stem-cell harvest.
The application that may appear most pertinent in the setting of CO poisoning is the extracorporeal membrane oxygenator (ECMO). These devices have been shown to play an important role in the clinical management of neonatal infants whose lungs are not developed enough to provide the physiologic function of oxygen absorption and carbon dioxide excretion. An example of such a device and a brief description of its principles of operation can be found at the following Internet link. http://www.ame.hia.rwth-aachen.de/index.php?id=267&type=98&L=1&L=1
It should be noted that the administration of 100% oxygen through a tight-fitting non-rebreather mask reduces the elimination half-life of carboxyhemoglobin to an average of 60 minutes, while HBO at a pressure of between 2.4 and 3 atmospheres reduces the elimination half-life of carboxyhemoglobin to an average of 20 minutes. Based on a five half-life carboxyhemoglobin elimination end-point, this would on average require five hours of 100% oxygen administration or 100 minutes of HBO at pressures noted above.
All of the existing treatments for carbon monoxide poisoning have some drawbacks. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.
It is, therefore, an outstanding object of some embodiments of the present invention to provide a system for the treatment of carbon monoxide poisoning in an efficient and effective manner.
Another object of some embodiments of the present invention is to provide a system for the treatment of carbon monoxide poisoning in a cost effective manner.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto, it being understood that changes in the precise embodiment of the invention herein disclosed may be made within the scope of what is claimed without departing from the spirit of the invention.